The present invention is directed to circuit interrupters, and more particularly to circuit interrupter operating mechanisms.
Circuit interrupter operating mechanisms are used to manually control the opening and closing of movable contact structures within circuit interrupters. These operating mechanisms will rapidly open the movable contact structure and interrupt the circuit in response to a trip signal from an actuator or other device. To transfer the forces when manually controlling the contact structure or when an actuator rapidly trips the structure, operating mechanisms employ powerful operating springs and linkage arrangements. The spring energy provided by the operating springs preferably provides a high output force to the separable contacts.
Commonly, multiple contacts, each disposed within a cassette, are arranged within a circuit breaker system for protection of individual phases of current. The operating mechanism is positioned over one of the cassettes and generally connected to all of the cassettes in the system. Because of the close position between each of the cassettes, and between each cassette and the operating mechanism, the space available for movable components is minimal. A typical problem for the rotary type circuit breaker is that minimal space is allowed for the operating mechanism, while the rotor design requires a high output from the operating mechanism to close the circuit breaker contacts. Circuit breakers of the prior art have addressed this problem by increasing the size of the breaker to accommodate the larger operating springs.
When closing the contacts, the circuit breaker operating handle is normally rotated to its xe2x80x9cfull closed positionxe2x80x9d. However, this is not always the case. The operator manipulating the handle may move the handle to less than the full closed position or may move the handle to the fully closed position in a slow manner. In either case, the operating mechanism may close the contacts, but with less force than if the handle was moved to the fully closed position. By controlling the relationship between the handle position and contact movement, a more efficient higher-output mechanism can be obtained.
The above discussed increased mechanism efficiency is achieved by a circuit breaker operating mechanism comprising a movable handle yoke, a mechanism spring extending in tension from the handle yoke to a pin, and a lower link extending from the pin to a crank operably connected to a contact arm bearing a movable contact. The crank is positionable in open and closed positions, being in an open position when the movable contact is separated from an associated fixed contact and being in a closed position when the movable contact is mated to said associated fixed contact. The circuit breaker further comprises an interface formed on said crank and a blocking prop having a first surface that engages said interface, the first surface preventing the crank from rotating towards the closed position.